The present invention generally relates to stress monitoring systems, and more specifically, to a fracture ring sensor and a method of using the same to detect out of tolerance forces.
Deflection, torque, and insertion forces are important characteristics of various components in many products for which there are specific critical tolerances. Detecting cases where these deflection, torque, or force tolerances have been exceeded can be important to maintaining a product and to prevent unsafe operating conditions. A printed Circuit Board Assembly (PCBA), for example, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks, or signal traces etched from copper sheets laminated onto a non-conductive substrate. The electronic components can include circuit elements such as capacitors, resistors, or active devices. Damaging the PCB during manufacture, installation, or handling can cause these electronic components or the PCB itself to fail.
One type of failure in the printed circuit board assembly is a strain-induced failure. Strain-induced failures can be caused by subjecting the PCB to sufficiently large deflection, torque, insertion, or shock forces (also known as out of tolerance forces). These strain-induced failures can result, for example, in cracked BGA (ball grid array) solder joints, intermittent opens of conductive traces and joints, cracked printed circuit boards (PCB) and cracked capacitors. Inadvertently operating a damaged PCB or component often exacerbates the problem as powering damaged circuitry can cause further damage to the equipment as well as to electrically coupled components. Damage associated with strain-induced failures reduces overall device yields and profitability.
To ensure product quality and reliability, PCB and component manufacturing and handling standards provide product specific critical tolerances that should not be exceeded. Monitoring for, and detecting, cases where deflection, torque, or other force tolerances have been exceeded is challenging but is necessary to maintain a profitable product line and to prevent unsafe operating conditions.